Dimmer for regular fluorescent lighting?

In a nutshell, no. The fixture needs a dimmable ballast. A non-dimmable ballast will not allow the lights to dim. Even though some lamps will dim slightly, you will drastically shorten the life of both the lamps and the ballast if you use a dimmer switch.

Many CFLs are dimmable because they have a dimmable ballast. LEDs are dimmable because of the driver (similar to a ballast). Otherwise, they would not work on a dimmer switch.

A regular dimmer can't be used.

FWIW, I was a photographer and moved to a loft space in a downtown office building. When the space was being built out, the management insisted that there be the same quantity of two tube 48" flourescent fixtures in the suspended ceiling as there would be if the space was being used for an office.

I thought they would be way too bright but had no choice. I was right...they were way too bright for my purpose so I bitched mightily to the building management. They had the maintenance people replace one (two?) of the tubes in the fixtures with what they referred to as a "phantom" tube. I do not recall the ballasts being replaced, just the tube (and I don't recall if it was one or both tubes) but I could be wrong, it has been 40 years.

The result was markedly reduced light; not variable, just dimmer.

Phantom tubes are plain glass tubes with a bi-pin base to fit fluorescent fixtures and a wire conductor in the center of the tube. They produce no light and draw no power, but allow the fixture wiring and ballasts to be untouched. This allows only one lamp to illuminate, thus, reducing light output and dimming the room and/or area, depending on how many are replaced.

This must be why they call you Meanie

And this too. Shame, shame.

A dimming ballast has to be used. The reason is that the voltage applied to the lamps has to be kept high enough to keep the lamps on while the lamp current is varied.

TK